The present inventions relates generally to an apparatus for equalizing the tension in a web of material, and more particularly to apparatus of the type which is used to equalize variation in tension across the width of a traveling web.
In general, modem apparatus for forming and/or processing webs of material such as paper, fabrics and the like, require that the web have substantial width and that the web travel at a very high speed, all for the purpose of reducing the costs of forming or processing the web on a per unit basis. While these increases in the width and speed of the traveling web enhance manufacturing costs, these same increases also tend to increase variations in the tension across the width of web which, if not equalized or compensated for, can have adverse effects on the forming and/or processing of the web. These tension variations may be caused during the manufacture of the web or mechanically induced while the web is travelling through a variety of processes.
For example, in a typical apparatus for forming a web of paper, the traveling web of paper is passed around and in contact with the surface of a heater roller, and variation in the tension of the traveling web across its width can result in the web being pressed against the surface of the heated roll with unequal forces so that the heat from the heated roll is applied unevenly to the web across its width. Usually the inherent variation in the tension of the web will result in the outermost edge of the web having the least tension so that they tend to flap, but such inherent variation can cause other undesirable results, depending on the type of web being formed or processed (e.g. paper, fabric, etc.), and the particular application, all as is well known to those skilled in the art.